Retailers pounce on the phenomenon, offering the eyesores as a lighthearted, cozy, often ironic way to celebrate the holidays. Ugly Hanukkah sweaters have appeared as well.

The tipsy crowd leaned in to take a gander at contestant No. 1: Natalie Novoa wassporting a flashing Christmas sweater bedazzled with pompoms, sequins and a stuffed gingerbread man.

With Christmas fast approaching, she twirled on a chair showing off her forest green pullover as it twinkled red, blue and green — lighting up the dark Silver Lake bar. She was vying with four other holiday-hued patrons this week for the coveted title of "ugliest holiday sweater" at the packed Thirsty Crow bar on Sunset Boulevard

"It's phenomenally, outrageously heinous," said Novoa, 35, beaming down at the grinning snowman perched on her sweater's left shoulder. "Tragic, in the best way."

Not long ago, eye-searing holiday sweaters were worn to Grandma's house and then immediately exiled to the closet. Now the young and hip snatch them up as an ironic alternative for Christmas bashes that often require suits and tight cocktail dresses.

The ugly Christmas sweater is a hipster phenom that has now become a holiday tradition of its own. Hundreds of retailers across the nation are hawking the sweaters and accessories, how-to books have popped up, and revelers are staging themed parties, contests and events that celebrate — and poke fun at — the holiday staple.

Las Vegas; Denver; Memphis, Tenn.; and even Moscow hosted ugly sweater 5K runs this month for charity. Ellen DeGeneres just emceed an ugly sweater fashion show on her talk show and gave a spectacularly odious version to Christina Aguilera.

Ugly sweater pub crawls across the Southland are attracting drinkers decked out in their tacky finest. A Los Angeles rock band even dubbed itself "The Ugly Sweaters."

Fraser Ross, owner of the boutique chain Kitson, said the ugly sweater party has replaced the tree-trimming parties of old.

"It's the new theme for hostesses who are trying to bring the mostest to holiday parties," he said. "It's like having a Halloween party during Christmas."

San Diego clothing brand Tipsy Elvesoffers humorous and sometimes raunchy designs for $65 a pop. Bestsellers include reindeer dancing in a conga line and a multitasking Santa spelling out "Merry Christmas" in the snow as he relieves himself. There's even an elf sweater for dogs.

"The majority of people buying are in their 20s or 30s who are sort of making light of what can be a serious holiday. It gives them an excuse to wear something funny," co-founder Evan Mendelsohn said. "It's not going to die like a normal fashion trend."

Even Hanukkah is not immune.

In October, Berkeley clothing label GeltFiend (named for the foil-wrapped chocolate coins Jewish children receive during Hanukkah) was launched after owner Carin Agiman spent years jealously eyeing the unhinged woolen numbers made for Christmas.

"I have a lot of non-Jewish friends, so I get invited to a lot of ugly Christmas sweater parties," Agiman said. "There's been a lot of pent-up Jewish angst over not having some equivalent ugliness."

Now, shoppers can shell out $60 for a sweater featuring Hasidic snowmen (complete with beards and long side curls) or $65 for a dreidel cardigan.

Agiman said many probably had a secret love of the cheesy sweaters all along, but can now wear them — ironically — in public. Or maybe the sweaters evoke the nostalgia for childhood. And despite the high-spirited fun, they still retain a warm spot in the closets of many people who fondly show them off every season.

"They're always super comfortable," she said. "If you had ugly high heels parties, you would have significantly fewer people participating."

Sweater aficionados trace the fad back to 2001, when three Canadian college students threw an ugly-sweater-themed shindig in Vancouver. It spread from there, especially among older teens and twentysomethings.

"In the United States, California is the hub of the ugly Christmas party sweater," said Anne Marie Blackman, who co-wrote the recently released book "Rock Your Ugly Christmas Sweater" and designs ugly knits that have been worn by comedians Jimmy Fallon and Rosie O'Donnell.

Saima Bari, 30, of Santa Monica figures she's been to at least 15 ugly sweater get-togethers. Among her collection of nine wacky sweaters, the UPS store clerk said, favorites are a "menage a trois" pullover featuring three overly affectionate reindeer and one with three cat heads all wearing Santa hats with bells.

"It sounds kind of crazy," Bari said. "But it's a nice change from getting super dressed up and fancy and going to a black tie party. And having to buy extravagant holiday outfits."

Not that ugly sweaters are cheap nowadays. The most grotesque ones can fetch hundreds of dollars.